Normal Concentrations of Some Trace Metals in Human Urine: Changes Produced by Ethylenediaminetetraacetate *

Interest in the biologic role of trace elements prompted an investigation of their renal excre- tion. Preliminary qualitative analysis revealed that except for cobalt the entire first transition series of metals, namely, titanium, vanadium, chromium, manganese, iron, nickel and copper, were detectable in most human urines. In addition the heavier transition metals, molybdenum and silver, as well as the related metals, zinc, cadmium, tin and lead, were ordinarily present. A method was evolved by which the urinary concentrations of such metals could be quantitatively estimated. The procedure included initial chemi- cal concentration followed by spectrographic anal- ysis. Contamination was minimized by careful preparation of equipment and reagents. Since extraneous iron and copper were particularly difficult to avoid and since these two metals had frequently been studied by other techniques, no attempt was made to measure them spectrographically. The exclusion of significant positive contamination, the demonstration that the low renal excretion of cobalt permitted its use as an internal standard, and the determination of standard working curves and recovery data for each metal constituted the control data for the assay procedure. Estimations were less satisfactory for chromium and titanium than for the remaining nine metals.